By: Yimo Liu

In 2022, an underwater volcano exploded in the South Pacific island nation of Tonga, causing lightning to fly up into the air about 20-30 kilometers above sea level. This reached the level of the atmosphere where airplanes fly, or probably higher!

The lightning from the volcano’s eruption plumes was created by the plumes themselves. They hit each other during the eruption which created static electricity. When there is enough static electricity, lightning can be created. That’s why the volcanic eruption changed into lightning striking.

Alexa Van Eaton led a group of researchers that observed how high the Tonga eruption’s lightning was. She’s a volcano scientist at the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Washington.

To understand how high the lightning went, Van Eaton and her group studied a few different types of data. The data showed that the lightning only started about 20 kilometers above sea level. Air pressure at that height is usually too low to form lightning “leaders.” Channels of hot plasma make up for the lightning during thunderstorms. “The rising eruption plume may have increased the air pressure over the volcano,” says Van Eaton. “That might have been enough to create lightning leaders at strangely high altitudes.”

“In those eruption data, we’re seeing stuff that we’ve never seen before,” says Jeff Lapierre. He’s a coauthor on the study. He’s also the principal lightning scientist in Advanced Environmental Monitoring. It’s a company based in Germantown, Maryland.

“The eruption has ‘completely changed the way we think of how natural events can change the atmosphere’, ” Lapierre says. ” It has also changed ‘the environment where we thought lightning could exist.”